Monday, May 11, 2009

Giant Eye in Space

The Hubble Space Telescope's legendary Wide Field and Planetary Camera 2 has produced one of its last images, a gorgeous shot of a planetary nebula.The nebula, a colorful cloud of gas and dust named Knockout 4-55 (or K 4-55), has an eye that appears to be looking right back at Hubble. The image was taken May 4 and released today.Monday, NASA aims to send the space shuttle Atlantis to Hubble, where astronauts will replace the camera with the Wide Field Camera 3, among other upgrades and fix-it projects. At a press conference, space agency officials said the camera will make one last image tomorrow, of a nearby galaxy named IC 5152, but that image won't be released immediately.Planetary nebulas have nothing to do with planets. They were named so because in early telescopes, they had the fuzzy look of planets in our outer solar system. In fact planetary nebulas sit throughout our galaxy. This one contains the outer layers of a red giant star that were expelled into interstellar space when the star was in the late stages of its life.Ultraviolet radiation emitted from the remaining hot core of the star ionizes the ejected gas shells, causing them to glow.

In the specific case of K 4-55, a bright inner ring is surrounded by a bipolar structure. The entire system is then surrounded by a faint red halo, seen in the emission by nitrogen gas. This multi-shell structure is fairly uncommon in planetary nebulae.

The Wide Field and Planetary Camera 2 instrument was installed in 1993 to replace the original Wide Field/Planetary Camera. Among its iconic images:Eagle Nebula's "pillars of creation."Comet P/Shoemaker-Levy 9's impacts on Jupiter's atmosphere.The 1995 Hubble Deep Field – the longest and deepest Hubble optical image of its time.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. Images are processed at the Space Telescope Science Institute, which conducts Hubble science operations.